Estimate Force for Spinning Forming

This may be a complex calculation, beyond my experience. Some of these references may help.

Welcome to CR4. Your diagram was very clear, and the question is among the best I have seen.

(A very minor note: the drawing is of a torispherical head rather than elliptical. To the untrained eye, these are almost alike, and there would be only small differences in the forming forces, which would depend on how close the forming balls are to each other as the operation progresses.)

The best CR4 experts for this would likely be Abdel Halim Galala and Nick Name.

You might ask these guys: Global Metal Spinning Solutions, Inc. or DENN USA Metal Forming:Machinery Program Overview.

I've never seen metal formed the way you have drawn it. All the metal spinning I've seen is done by forcing the metal to conform to a round mandrel that is the final shape of the part, sometimes using heat.

Tornado is correct, the two gentlemen he names likely are the most knowledgeable on the subject.

http://www.youtube.com/watch?v=um-biLfru-c

http://www.youtube.com/watch?v=XsCFze4zkzk&feature=related

http://www.youtube.com/watch?v=soCh9U2TU48&feature=related

That makes two of us.

At the risk of being tangential, there is a metal forming technique in sheet metal forming called the English Wheel. The results are wonderful one-off pieces. the practicioners are more of an artist, than a technician.

The more technical one is explosive forming. The explosion takes place in water, and in one step the sheet metal is plastered on the inside of the form. Again, it is the work of artists of an "ahem" different kind. Not for the timid, that's for sure.

Then there is the good old-fashioned stamping, you seems to want to avoid.

English wheels form gentle curves, not end caps.

"Explosive forming" is more likely explosive joining, which is how they used to make the nickel clad copper coins. It joins two metals with no intermediate processes.

I'll give you hydroforming, if you want to look that up.

But, the term is metal spinning. Ok, mis-used as spinning forming.

OOPS.

You are right about explosive forming.

I stand corrected.